3/8-32 tap drill size
Use a 11/32 drill (0.3438 in) for a 3/8-32 cutting tap at 75% thread.
| Tap type | Drill | Decimal (in) |
|---|---|---|
| Cutting tap, 75% thread | 11/32 | 0.3438 |
| Cutting tap, 50% thread (hard material) | T | 0.3580 |
| Roll / form tap, 65% thread | 23/64 | 0.3594 |
- Pitch
- 0.7938 mm (32 TPI)
- Major Ø
- 0.3750
- Pitch Ø
- 0.3547
- Minor Ø
- 0.3412
Common questions
- What size drill for a 3/8-32 tap?
- Use a 11/32 drill (0.3438 in) for a 3/8-32 cutting tap at 75% thread.
- What drill for a 3/8-32 roll (form) tap?
- About 0.3612 in; the nearest standard drill is 23/64. Check your tap maker's table.
Other UNEF sizes
Drill sizes from Machinery's Handbook and ASME B1.1/B1.13M; roll tap sizes from the form-tap formula. Tap and insert makers' tables are authoritative.
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